THE DIAGONAL EFFECT 



right hind leg, therefore, stops, and the left hind leg 

 moves forward into position for the impulse, while 

 the right hind leg becomes the support. The right 

 front leg also becomes a support; but the left fore 

 leg extends forward to receive the impulsion. It 

 follows, then, that before the left hind leg has made 

 contact with the ground and taken over the duty of 

 impulsion, the horse is upon a diagonal biped. 

 (Figure 24.) 



In order, therefore, to execute the change of lead 

 from right to left, the cavalier should, at the instant 

 of change, lean to the right, in order to load the 

 right lateral biped. This, thereupon, becomes the 

 support, and leaves the left lateral biped unloaded 

 and off the ground for the very quick movement 

 called "change of foot in the air." This whole 

 motion, but especially the action of the left hind 

 leg, is so rapid that the eye cannot perceive the 

 relations of the different limbs. Even photography 

 is inadequate to show the action clearly. The cam- 

 era can, however, be made to exhibit the left hind 

 leg in the different parts of its stride. Thus in Fig- 

 ure 25, the left hind leg first disappears behind the 

 right; and next after that the right fore leg is flexed. 

 Finally, in Figure 26, the left hind leg is on the 

 ground, in front of the right and ready for propul- 

 sion. The left fore leg is already raised. It will ex- 

 tend forward as soon as the right hind leg has ar- 

 rived near the left, to assist as support and thus 

 allow the left hind leg to continue the impulse. 



197 



